title: Heterogeneous vasomotor responses of coronary conduit and resistance vessels in hypertension.
abstract: OBJECTIVE
  The purpose of our study was to investigate the relation between conductance and resistance coronary vasomotor responsiveness in hypertensive patients without atherosclerosis.
  
  
  BACKGROUND
  Although similar in morphology, conduit and resistance coronary vessels differ importantly in size, function and local environment and appear to be differentially affected in certain disease processes, such as atherosclerosis and hypertension. However, little is known about the effect of hypertension on contiguous coronary conduit and resistance vessels in humans.
  
  
  METHODS
  Changes in coronary blood flow (a measure of resistance vessel reactivity) and coronary artery diameter (a measure of conduit vessel reactivity) were investigated in response to graded infusion of the endothelium-dependent agonist acetylcholine (ACh) in 98 patients with normal coronary arteries.
  
  
  RESULTS
  In 31 normotensive, euglycemic patients, conduit and resistance coronary artery responses to intracoronary infusion of ACh were significantly correlated (r = 0.73, p = 1 x 10[-6]), although eight patients (26%) had constriction of conduit but dilation of resistance arteries at peak effect. In 28 hypertensive patients without left ventricular hypertrophy (LVH), conduit and resistance artery responses to ACh remained significantly correlated (r = 0.5, p = 0.006), although 12 patients (43%) had discordant findings. Finally, in 39 hypertensive patients with LVH, conduit and resistance artery responses to ACh displayed the lowest correlation (r = 0.38, p = 0.02), with 22 patients (56%) demonstrating conduit artery constriction and resistance artery dilation.
  
  
  CONCLUSIONS
  Despite angiographically normal coronary arteries, heterogeneous vasomotor responses (dilation and constriction) were demonstrated in contiguous conduit and resistance arteries in normotensive and hypertensive patients referred for cardiac catheterization because of chest pain. In addition to more severe endothelial dysfunction among conduit and resistance arteries, a greater frequency of discordant conduit and resistance artery responses and resistance vessel constriction was found with increasing severity of hypertension. Our study suggests differing mechanisms of endothelium responsiveness to ACh among conduit and resistance coronary arteries.
authors.affiliation: Department of Medicine, Albany Medical College, New York, USA. jhoughton@ccgateway.amc.edu
authors.forename: J L
authors.initials: JL
authors.lastname: Houghton
authors.forename: C A
authors.initials: CA
authors.lastname: Davison
authors.forename: P A
authors.initials: PA
authors.lastname: Kuhner
authors.forename: M T
authors.initials: MT
authors.lastname: Torossov
authors.forename: D S
authors.initials: DS
authors.lastname: Strogatz
authors.forename: A A
authors.initials: AA
authors.lastname: Carr
mesh_terms: D000109:Acetylcholine / Q000008:administration & dosage / Q000494:pharmacology; D015331:Cohort Studies; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000503:physiopathology; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology*; D003331:Coronary Vessels / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000503:physiopathology; D005260:Female; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D006973:Hypertension / Q000000981:diagnostic imaging / Q000503:physiopathology*; D017379:Hypertrophy, Left Ventricular / Q000473:pathology / Q000503:physiopathology; D007261:Infusions, Intra-Arterial; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology; D010496:Pericardium / Q000187:drug effects; D011446:Prospective Studies; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects; D014666:Vasomotor System / Q000187:drug effects / Q000503:physiopathology*
chemical_list: D000109:Acetylcholine